A new study from Finland has found that people diagnosed with early-onset dementia—before age 65—live for very different lengths of time depending on the type of dementia they have.
The research, published in the Journal of Neurology, Neurosurgery & Psychiatry, shows that while older people with dementia typically have shorter lifespans, the impact of the disease is actually greater for younger adults compared to their peers of the same age without dementia.
Globally, around 5% of all dementia cases are considered early-onset.
Unlike dementia in older adults, which has been widely studied, little is known about how long people live after being diagnosed at a younger age or what factors influence survival.
To address this gap, researchers reviewed data from two Finnish hospital districts, analyzing 12,490 clinic visits made between 2010 and 2021.
They identified 794 confirmed cases of early-onset dementia, including Alzheimer’s disease, frontotemporal dementia, Lewy body dementia, and vascular cognitive impairment (sometimes called “mixed dementia”).
Each case was compared to ten similar people from the general population—matched by age, sex, and location—who did not have any neurodegenerative disease, totaling nearly 8,000 comparison participants.
During the study period, 215 people with early-onset dementia died. On average, patients lived nearly nine years after diagnosis, but survival time varied depending on the type of dementia.
Those with frontotemporal dementia or Lewy body dementia had the shortest survival—around seven years. People with both frontotemporal dementia and motor neuron disease (ALS) lived only about two years on average.
By contrast, individuals with Alzheimer’s disease lived nearly ten years after diagnosis, while those with vascular cognitive impairment lived the longest—over ten years on average.
When compared with people of the same age without dementia, those with early-onset dementia were 6.5 times more likely to die from any cause during the study period.
Risk levels differed by subtype: mortality was almost 14 times higher for those with frontotemporal dementia and about four times higher for vascular dementia.
The study also found that being male, older, or having several other health conditions increased the risk of death—but these factors were not unique to early-onset dementia.
Only diabetes, already known as a dementia risk factor, was linked to a shorter survival time within this group.
The researchers emphasized that the diagnosis itself had the strongest impact on survival. “Although older patients may appear to live fewer years after diagnosis, early-onset dementia has a much greater effect on mortality compared with others of the same age,” they wrote.
While the study was observational and cannot prove cause and effect, it provides valuable new insights.
The researchers say accurate, up-to-date information about survival rates is essential for planning healthcare services, improving patient care, and guiding future clinical trials for people living with early-onset dementia.
If you care about dementia, please read studies about low choline intake linked to higher dementia risk, and how eating nuts can affect your cognitive ability.
For more information about brain health, please see recent studies that blueberry supplements may prevent cognitive decline, and results showing higher magnesium intake could help benefit brain health.
Source: British Medical Journal.
